Aberrant neuronal connectivity is associated with a number of neuropathological and neuropsychiatric diseases/disorders. Inefficient developmental connectivity, misdirected connectivity, or disrupted and degenerated connectivity can account for losses of normal neuronal communication and subsequent losses of mental or physical health. Altered expression of axonal guidance proteins, neuroinflammation, neuronal toxicity and glial disturbances may be involved in inadequate neuronal connectivity. The goal of the work described in this application is to develop an instrument platform that can both enumerate development or loss of axons and the kinetics of these changes in response to molecular and cellular modifiers. The proposed grating coupled surface plasmon resonance (GCSPR) and grating coupled surface plasmon coupled emission (GCSPCE) instrumentation with a microflow biosensor chip will be developed and validated for quantification of developmental axonal outgrowths among punches of brain regional sections as well as loss of connections previously established. Up to five 1-3mm punches can be placed on the 1 cm2 biosensor gold chip precoated with extracellular matrix proteins and specific molecules (guidance proteins) or cells (microglia) spotted at specific locations. Lack or loss of axonal connections will be kinetically monitored by SPR and presynaptic and postsynaptic antigens can be assayed by SPCE with fluorochrome conjugated antibodies to neuronal antigens. The geometrical placement of specific brain regions will be identified so that preferential regional interactions can be quantified. The planned device to assess neuronal circuitry is built upon extensive experience with SPR microarrays that can characterize presence of single cells and their released products. The work described will produce instrumentation capable of providing a more complete and coherent picture of differential neuronal connectivities to provide a more comprehensive view of neuronal communications, which will reveal new opportunities for therapeutic interventions.